Granted Patent B2

US 8,654,689 · App. 12/892,874 · Granted Feb 18, 2014

Inventors: Michael L. McCloud (Boulder, CO); Vijay Nagarajan (Boulder, CO)

Assignee: Rambus Inc.

Abstract

Claims (21)

1. A method for cancelling interference from a received baseband signal in a CDMA system, comprising:

generating at least one composite interference vector (CIV) by combining estimates from interfering subchannels,

generating a soft-cancellation operator, and

performing a soft cancellation of the received baseband signal to output an interference-cancelled signal,

wherein the estimates are derived from a Rake receiver.

2. The method recited in claim 1 , wherein each finger of the Rake receiver is matched to at least one of a time delay and a base station spreading code.

3. The method recited in claim 1 , wherein generating at least one CIV comprises generating at least one of soft estimates and hard estimates from the interfering subchannels.

4. The method recited in claim 1 , wherein generating at least one CIV comprises generating at least one or more soft estimates corresponding to interfering user subchannels from each base station tracked by a cellular handset.

5. The method recited in claim 1 , wherein the at least one of soft estimates and hard estimates is derived from a selected one of a Rake receiver, an equalizer, and a detector matched to the communication protocol and channel conditions of the received baseband signal.

6. The method recited in claim 1 , wherein the at least one CIV is generated using at least one of a symbol estimator, a sub channel selector, a fast Walsh transform, and a PN coder.

7. The method recited in claim 6 , wherein the at least one CIV is generated using a symbol estimator employing at least one of Rake processing, receive diversity and equalization.

8. The method recited in claim 1 , wherein performing a soft cancellation comprises at least one of subtractive and projective interference cancellation.

9. The method recited in claim 1 , wherein the soft cancellation operator comprises a soft-projection matrix generator or an interference-cancelling operator configured for selecting a soft weight that increases a post-processing SINR.

10. The method recited in claim 1 , wherein the received baseband signal is coupled to a first Rake finger and generating the at least one CIV comprises generating the at least one CIV from at least one Rake finger that does not include the first Rake finger.

11. The method recited in claim 1 , wherein generating the at least one CIV comprises deriving the estimates from at least one of a Rake receiver, an equalizer, a receiver employing receive diversity, a receiver employing transmit diversity combining, and a receiver employing space-time decoding.

12. The method recited in claim 1 , wherein generating the soft-cancellation operator comprises generating a soft-projection matrix to operate on a received data vector, the soft-projection matrix having the form F(λ)=I−λss*, where I is an identity matrix, λ is a weight, and s is a CIV.

13. The method recited in claim 12 , wherein generating the soft-cancellation operator comprises determining the weight λ by maximizing a post-processing SINR.

14. The method recited in claim 13 , wherein generating the soft-cancellation operator comprises determining the weight λ by maximizing a post-processing SINR for a handset operating in a soft-handoff mode.

15. The method recited in claim 1 , wherein performing the soft cancellation further comprises coupling the interference-cancelled signal to at least one of a combiner and a Rake receiver.

16. The method recited in claim 15 , further comprising combining a plurality of interference-cancelled signals.

17. The method recited in claim 1 , wherein the CDMA system is configured to implement receive diversity and equalization.

Assignments (1)

Continuity (9)